Disabling certain cores on Z170 motherboard?

Hey, I’m curious if there is a straightforward way to disable certain CPU cores on an ASRock Z170 Gaming K4/D3. This board is coffee-lake modded to run an 8700k, however I noticed one core on that particular CPU is partially broken and only stable at a significantly lower frequency than the others.

Are there any mods to the BIOS itself, or perhaps efi vars I can edit via, for example, grub-mod-setup_var, to disable that one bad/worse core?

Thanks!